The present invention is directed to a self-aligning tulip cover for interconnecting and aligning a spider assembly, a tulip body, and a boot, as well as a closed tripod constant velocity joint incorporating the self-aligning tripod joint tulip cover.
Closed tripod joints have been popular for use in half-shaft assemblies of front wheel drive motor vehicles. A tripod joint is commonly used because of its ability to transmit torque at a constant velocity, in addition to allowing the joint centerline to move in an axial direction. This joint centerline movement is primarily caused by the movement of the suspension system in jounce and rebound and the movement of the power train on its mounts.
In addition to transmitting torque and allowing joint centerline movement axially, the plunging joint characteristics of a tripod joint in a front wheel drive vehicle also enable the tripod joint to act as an isolator for vibrations. These vibrations are generated by the power train due to its inherent unbalance and have to be isolated from the suspension system in order to eliminate any noticeable disturbances to the vehicle occupants.
The cover of a closed tripod joint has, in the past, been used to retain the tripod assembly inside the tulip body during operation. Prior art designs exist where a convoluted cover is assembled to the tulip body in such a manner that the convolutes of the cover fit on the irregular contours of the tulip forging. This results in an expensive tripod joint as well as one which may be difficult to assemble. Furthermore, the sealing boot may have to be lobed in these prior art designs to conform to the irregular contour of the tulip body, increasing the expense of manufacturing the boot and assembling it to the closed tripod joint.
Additionally, in prior art designs, the boot generally has an outer diameter greater than the respective outer diameters of the tulip body and the tulip cover. Thus, when the tripod joint is layed down or dropped, the boot experiences the load and impact, very likely resulting in a certain amount of boot damage during handling in assembly plants.
Another consideration in the design of closed tripod joints is that it is paramount for the proper lubrication and function of the closed tripod joint that an airtight seal exists between the sealing cover and the tripod body. Typically, this sealing has been achieved in the past by interconnection of one end of the boot to the outer surface of the tulip body or to the outer surface of a sealing cover mounted coaxially with the tulip body.
Several examples of prior art closed tripod joints, as well as tulip covers and boots therefor, may be found in Goguet, U.S. Pat. No. 4,280,340 issued July 28, 1981; Westercamp, U.S. Pat. No. 4,083,202 issued Apr. 11, 1978; Dore, U.S. Pat. No. 4,320,632 issued Mar. 23, 1983; Kobayashi, U.S. Pat. No. 4,224,806 issued Sept. 30, 1980; and Hirai, et al., U.S. Pat. No. 4,196,598 issued Apr. 8, 1980.
What is needed, therefore, is an inexpensive tripod joint tulip cover which is self-aligning and provides a good seal with the tulip body. Furthermore, what is needed is such a tripod joint tulip cover which is easily interconnected with a boot having a regular circular contour. Additionally, what is needed is a tripod joint tulip cover which permits the interconnection thereto of a boot having a smaller outer diameter than the respective outer diameters of the tulip cover and tulip body so as to protect the boot from damage during assembly and handling.